


Other Avenues of Study (History)

by fyrefalcon



Series: fyrefalcon's 2019 setleth week [6]
Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Accidental Voyeurism, Desk Sex, F/M, Fluff and Smut, Masturbation, Oops, Porn with Feelings, Post-Time Skip, Public Sex, byleth always gets what she wants, seteth is so anxious
Language: English
Status: Completed
Published: 2020-02-02
Updated: 2020-02-02
Packaged: 2021-02-27 20:08:03
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,761
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22521508
Author URL: https://archiveofourown.org/users/fyrefalcon/pseuds/fyrefalcon
Summary: Hejust couldn’thave sex with Byleth in the library of all places, like a hormonalyouth--She slipped past him, and when she turned to perch on the edge of the desk, she’d already unfastened her shorts, slipping them down her legs along with her tights as she planted her bare ass on the desk, pinning Seteth in place with a challenge in her eyes.Seteth heard his blood pound in his ears.
Relationships: My Unit | Byleth & Seteth, My Unit | Byleth/Seteth
Series: fyrefalcon's 2019 setleth week [6]
Series URL: https://archiveofourown.org/series/1577812
Comments: 16
Kudos: 165





	Other Avenues of Study (History)

**Author's Note:**

> they can have sex on other desks besides seteth's, right...? 
> 
> props to the beautiful [NSFW art](https://twitter.com/drthealovezone/status/1186502781445857280) that inspired this scene. Faculty meeting indeed. <3

The warm light of the library spilled out into the dark hall. 

Seteth turned into the room, scanning for occupants, and when the tables appeared empty, he made a beeline for the staircase. Even before Solon had shamed him by revealing his flawless infiltration of the faculty, Seteth had possessed enough authority to access the whole of the library. 

But never before had he unhooked the chain for the second floor with a trembling hand.

Byleth was already perched above him, leaning on the railing, and he watched her as she gazed at the globe that had been installed over five hundred years ago, her face impassive.

He couldn’t fathom what she might be thinking. He wondered if she would always remain a mystery to him or whether, through sheer repetition and proximity, he would begin to understand the workings of her inner mind.

He joined her a moment later, bending down to place a chaste kiss at her temple. “This is profoundly unwise.” 

She turned to face him. “You didn’t have to come.” As she spoke, she leaned herself into him, lacing her fingers with his own, pressing her lips to the curve of his jaw and guaranteeing he wouldn’t leave, no matter how unwise it seemed.

He sighed. “You know I can’t say no to you.” It was this, or another night in some abandoned corner of the monastery, watching Byleth shiver from the cold. “Not about this. Not when both of us could be lost tomorrow, and--”

“Shhh.” She placed her hand on his face, gentle. “This is not the time for thoughts like these.”

Seteth sighed again, knowing she was right. It was just so hard for him to shake his fear for her safety in these savage times, and he knew it overshadowed everything, a companion to the miasma of unease that clung to the monastery and its inhabitants like a fog.

Byleth cleared her throat. “We could just be honest...” 

“No.” He shook his head. He couldn’t face their former students, couldn’t face Flayn. It was...inadvisable. “Not right now.” Not ever, while they were all together in this monastery, fighting this war.

“We could try your office again.” 

“And have Flayn let herself in when she thinks I’ve fallen asleep because I don’t respond to her knock?” 

His face burned just thinking about it--about the confused look on his daughter’s face when she’d realized her professor had been locked in the office too. How quickly Byleth had moved.

She shrugged. “You’re the one who cares if we get caught.” He watched as something akin to mischief sparkled in her eyes. “I’ve got us set up near the window.” 

He allowed her to lead him back into the rows of books furthest from the staircase. 

“I assessed the situation this morning--we should have the most privacy over here.” 

He couldn’t believe he was following her here to do this. It made him feel addled. But of course Byleth’s tactical mind would have thought about sight angles and the way sound carried before suggesting this location. 

Tucked between the window and the end of the shelves, there was a small desk overlooking the grounds. Before Tomas’s departure, it had been his; now Byleth sometimes worked here, or Seteth, when he didn’t want to be interrupted. 

The surface was empty save a candle and a single tome--Byleth had opened the book that Seteth had confiscated from Claude years earlier, and Rhea’s imposing form regarded him accusingly from the pages.

_ Goddess. I should be looking for her, not preparing to take Byleth in the library... _

Seteth reached over, shutting the book, trying to shut off his thoughts. Had his priorities truly shifted so profoundly?

The truth of his background was a conversation for another time. He didn’t even want to consider why Byleth’s attention had been drawn to the illustration. If she suspected. What she already knew. 

Byleth watched, face still impassive, as he slid the book into the top drawer. He spoke quietly. “We really should just...” He noticed his hand was still shaking. 

He  _ just couldn’t _ have sex with Byleth in the library of all places, like a hormonal  _ youth _ \--

She slipped past him, and when she turned to perch on the edge of the desk, she’d already unfastened her shorts, slipping them down her legs along with her tights as she planted her bare ass on the desk, pinning Seteth in place with a challenge in her eyes. 

“We really should do what, Seteth?” Her voice was conversational and calm. 

Seteth heard his blood pound in his ears. 

Byleth tipped her knees open, and Seteth couldn’t look at anything except the center of her, his internal monologue spinning into a single, high-pitched whine, blocking out his anxious protests. 

“Ah.”

Byleth didn’t break eye contact with him as she reached down, inserting a finger inside herself and then circling her own clit with her own wetness. 

Dimly, he perceived it as the challenge and the invitation it was.  _ Goddess, Byleth.  _

“You’re scandalous.” He took a step towards her, reaching for her hip. 

“If you don’t want to be here, you can leave,” she said, pleasuring herself slowly, her head tilted back, her eyes still meeting his. 

“No, I--” 

She leaned forward, pushing his shoulder so he stepped back. The back of his knees encountered the seat of the desk chair, and he sat, hard, his face eye level with Byleth’s center. 

He reached forward to help, wanting to feel the warmth of her body underneath his palms, and she regarded him with a stare that he’d encountered before. “Hands off.” 

Seteth sat back in the chair, very straight. He placed his palms on his own thighs, his earlier protests forgotten, as he braced himself for the show that was unfolding before him. The texture of his own clothing was very apparent under the pads of his fingers.

He yearned instead to feel Byleth’s skin. 

She was dressed down for her evening work, not in her nightclothes, but not in her battle regalia either. Her short black shirt dipped provocatively, displaying her cleavage to perfection, especially leaned forward as she was, and her middle was bare, and now the rest of her as well, down to her knees, where her tights bunched low on her thigh, shorts discarded. 

She supported herself with one arm as she touched herself with the other, one leg drawn up to give herself better access to her core, and Seteth watched as her center flushed, her clit becoming round and engorged, and her inner lips darkening, as she pleasured herself inches away from his face.

Seteth wondered how he had managed to wait so many years to indulge himself, indulge her. She was a vision, spread out in front of him, and it was making him very, very uncomfortable. He shifted.

Byleth still regarded him with a heavily lidded gaze, watching his reaction carefully, one hand applying soft pressure to her own body--Seteth thought about how it would feel to follow the path she traced with her finger with his tongue and he couldn’t keep the shiver from running down his spine. 

His cock pressed into his pants uncomfortably. He shifted again, trying to adjust...and Byleth tutted. “Don’t.”

He could feel the blush high on his cheekbones as he watched her face contort with pleasure. 

She was too far away from him, and he could feel the heat of her in the air and the painful discomfort of his erection as it pushed into the seam of his pants. It made him very, very aware of his own arousal, and it was everything he could do to restrain himself from reaching out, from burying his face in her, to make her plead for him aloud in the quiet of the library. 

Now his hands were shaking for a different reason.

Byleth slid a finger inside of herself, and then another, and he watched as she hooked up into her own sweet spot, her breathing soft and irregular. There would be no question, were they overheard, what was transpiring. 

He wanted to shush her and make her scream. His agony over the situation was almost paralyzing. 

Fully committed to her own pleasure, Byleth’s head tipped back, and Seteth watched as her chest flushed, the splotchy redness that was indicative of her building arousal spreading across her skin. 

He wanted to kiss her, wanted to mark her neck, wanted--

She pressed her hips up into her own hand, humming, and he was close enough to see the twitch of her muscles as they telegraphed her pleasure. He watched as her cadence faltered, chasing her own release. 

She was so bold. So much bolder than any woman he’d ever been with, and he loved it just as much as it shocked him. Enough of his brain was online to remind him of his admission to Manuela... Here was Byleth, anything but quiet. Certainly not proper. 

He was  _ infatuated  _ with her. The long wait had been worth it. 

Her breath hitched, and Seteth knew she was close--so close, and then she was sighing quietly into the quiet air, the sound swallowed up by the loaminess of the books around them, and Seteth’s face was in her core, tasting her, feeling the aftershock of her orgasm ripple through her softness with his tongue. 

He licked her, almost panting with need, until she brushed him away, oversensitive. 

She pushed up to look at him, and Seteth knew the admonishment was coming. “You didn’t listen to me.” 

Her serious face didn’t shift, and her eyes were inscrutable. Seteth wondered if he’d misread the situation. For a moment, he felt a flicker of fear mingling with his acute need.

But then her face broke into a smile and she reached out, drawing him close, and he felt himself yearning into her as she brushed his hair off his face, already tacky with sweat and nerves and arousal. 

“Still think we shouldn’t, Seteth?” she murmured in his ear. 

His hands were already at his pants, unfastening them before pushing them down his legs. He was glad for the length of his tunic--at the very least, his bare bottom would not be exposed to the world were they to be intercepted. 

He looked into her face, wondering if she was ready for him, and she nodded. He guided himself into her, her cunt hot and wet and puffy from her orgasm, and it felt so good he couldn’t help but sigh, his long exhale fogging up the glass behind the desk. 

He hadn’t even considered that someone could be watching them through the window, and then Byleth was moving beneath him with a quiet moan, and his faculties were so wholly focused on the woman beneath him that thought he might not even care. 

He watched her face as he pulled back, pumping into her with slow strokes, feeling the glorious sensation of her wrapped around him, his cock deep into her wet heat, the hard desk under his hand, her legs crossed behind him at the ankle. 

Her thighs pulled him into her, setting the rhythm, and he was only too happy to comply as Byleth coaxed him, faster, faster. The drawers in the desk beneath them rattled as Seteth pounded into her, Byleth’s hips pressing up to meet him each time he pulled out and then drove home once again.

He moaned into her hair, clutching her close, surrounded by her warmth and her smell, soft and floral and comforting, and wished the rest of the world away so this moment could continue forever.

Byleth reached up to caress his face, recognizing the devotion in his eyes, leaning in, whispering “I love it when you fuck me like this” and Seteth pulled himself back from the edge, trying to brace himself once again, this time against the heat pooling in his lower belly.

He could feel his muscles working as he hilted into her, noticed the sound of his thighs clapping against her ample ass loud in the otherwise silent room.

He buried his face in her cleavage, kissing the curve of her breast, and she dug her fingers into his back as she came again, muffling her long release into the shoulder of his tunic. Her fingernails bit into his skin, even though the thick cloth of his uniform, and the pain mixed with the pleasure and became heavenly.

The marks would be easily hidden, but he would know they were there.

He could feel her warm breath through the fabric, and she pulled back to look at him, smiling and loose from her second release in a matter of minutes. He tensed with pleasure, biting back his moan but still murmuring “ _ ah, Byleth _ ” through clenched teeth, trying to keep himself  _ quiet  _ and knowing that he was failing utterly.

Her face was flushed and beautiful, and he looked at her as he came, orgasming inside of her and letting her watch as he floated down over the edge and he joined her in the softness of their mutual release. 

He pressed kisses to her face, feeling her delicate skin under his lips, tracing her cheekbones, her eyelids, her brows.  He was wholly absorbed in his love for her, and he wondered how long he could truly content his heart with these stolen moments in odd corners. He wanted to walk beside this woman for the rest of his life, not hide with her behind closed doors. 

Or on the second floor of the monastery library, late into the night.

When he felt himself soften inside of her, he pulled out, his cum pooling on the desk. A small part of him delighted in the insult to the former librarian; the rest of him looked around for a solution. Byleth had tucked a square of linen sheeting in the front of her satchel and he reached over to grab it. 

The woman truly did think of everything. 

He cleaned himself up and put himself to rights and handed the cloth to her. Following his lead, she restored herself to some semblance of respectability before using the cloth to wipe off the desk. “Serves this asshole right,” she said, chuckling. 

“Indeed.” Seteth smiled and pulled her into a hug, feeling the strength of her as she hugged him back, enjoying the moment of quiet, noticing the blissful stillness in his own mind as they sank into each other. 

On the first floor of the library, someone coughed.

Byleth and Seteth pulled away from each other, their eyes meeting--hers curious, his wide with alarm. As quietly as they could, they gathered their things and straightened their clothing, Seteth resettling the circlet on his head as he followed Byleth back downstairs. 

On the first floor, Seteth refastened the staircase chain behind him, and when he turned around, Linhardt was there, a book in one hand and a stumpy candle in the other. His face was shadowed with sleep, but that was hardly unusual.

The green-haired man blinked, catlike, as he took both of them in. Byleth was still and straight in front of him, and Seteth was careful to keep a professional distance between them.

“Oh. So _that’s_ what I was hearing.” Linhardt yawned. “Figures. Well, have a good night, Professor. Seteth.”

Byleth nodded. Her face was still impassive. “Goodnight, Linhardt.”

Seteth could only stare after the green-haired man who bowed to both of them again and then took his leave. “Goodnight.” He couldn’t believe Linhardt had been here the entire time, and hadn’t even bothered to investigate.

Beside him, Byleth laughed once through her nose.

Seteth’s face burned with embarrassment. When he found his voice, it was only a whisper. Horrified, he asked Byleth, “Do you think the others know?”

She nodded once. “I absolutely think they do. And if they don’t know now, they will soon.”

Seteth swallowed hard. “Well. Hopefully he will not mention it to Flayn.” 

She smiled up at him, and taking his hand, she led him out of the library. “Look on the bright side. It means next time it will be wiser to use a bed.” 

Seteth felt as though he was betraying himself as he considered what he wanted to say next. “I suppose. Though it won’t be half as hot as taking you on my desk, now will it?” 

Now Byleth looked surprised. And happy. “I think there’s time enough for both, my love.” 

Despite everything, Seteth returned her smile, allowing himself to believe her. "Indeed."

***

**Author's Note:**

> and thus concludes fyrefalcon's 2019 setleth week. hope you enjoyed! if you want updates about more setleth content or just want to see me fail at social media, come hang out with me on [twitter](https://twitter.com/fyre_falcon). 
> 
> ALSO! An unofficial Setleth zine is in the works! If you haven't already, please fill out the [interest survey](https://docs.google.com/forms/d/e/1FAIpQLScD8tmMvycHnwVnrU3piAN2bzM--j6Ar2eZoQJ1BPulJxrp0w/viewform) so we can do the good work of putting more setleth content into the world!


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